grounding

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Ryan Currin

Member
Location
Allston MA
My questions pertains to the grounding requirements of aircraft hangars. We are building 6 new aircraft hangars total distance 375 feet. Each one will have a new slab. There will be a new 7 bank meter service on one side for the entire structure. The local electrical inspector mentioned the need for eccentric grounds to be used. By code, what kind of grounding system do I need to install other than 2 ground rods at the service, cold water ground, and building of steel.

Thanks
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
As far as grounding electrodes you seem to have that covered unless you also have a concrete encased electrode.
As far a his mention of "concentric knockouts", you might review 501.30 for specific grounding requirements for Class 1 Hazardous locations.
 

Ryan Currin

Member
Location
Allston MA
I'm not sure what he meant, eccentric or concentric grounds. I would think this structure is treated as any other building with a slab and steel beams. I looked in the code under aircraft hangars and didn't see any mention of it. I don't plan on using a concrete encased electrode as the build of steel ground should cover that. Is there any lightning protection required that I'm missing?
 

Ryan Currin

Member
Location
Allston MA
Ya I'll talk to him to see what the hell he's talking about. This was over the phone today with him and I didn't get what he meant so I'll see him Monday. I'll let you know if it's anything out of the ordinary. Thanks for the help
 

kwired

Electron manager
Location
NE Nebraska
I'm not sure what he meant, eccentric or concentric grounds. I would think this structure is treated as any other building with a slab and steel beams. I looked in the code under aircraft hangars and didn't see any mention of it. I don't plan on using a concrete encased electrode as the build of steel ground should cover that. Is there any lightning protection required that I'm missing?

Read 250.50 carefully, if a concrete encased electrode is present you must use it, same for building steel.

Ground rods would not be required if you have CEE or steel though.


Don't know what is meant by concentric/eccentric grounds?
 

rlundsrud

Senior Member
Location
chicago, il, USA
Perhaps he was referring to eccentric panel knockouts, he was warning you to be sure to use bonding bushings as required for them. I am just speculating, but I can't imagine what else he might be referring to.

I have never seen static grounding cables in hangars, only at the self serve gas pumps.
 
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